The invention relates to vehicle windows, and especially to vehicle windows provided with a polymer profile on or adjacent at least one edge thereof.
Traditionally, fixed (i.e. non-opening) vehicle windows were glazed using a gasket which both fitted over the edge of the glass to hold it in position and engaged the bodywork of the vehicle. Such gaskets typically had an "H" section with the glass fitting into one recess of the "H" and the opposed recess of the "H" section engaged over a metal flange formed in the vehicle bodywork and extending around the periphery of the window aperture.
More recently, it has been common to glaze fixed vehicle windows adhesively, using a modem adhesive to bond the window to the metal bodywork. In this way, a rigid bond can be formed between window and body, with the window supplementing the strength and stiffness of the vehicle body. To provide an aesthetically pleasing trim, polymer profiles have been bonded to the glass to form a frame (i.e. a continuous, endless, ring) around the periphery of the window, with the adhesive used to bond the window to the car applied between the vehicle body and the polymer profile. More recently, it has been proposed to apply the adhesive directly between the vehicle body and the glass surface immediately inside the frame around the window formed by the polymer profile.
Polymer profiles used in bonded glazing systems may be preformed and then bonded to the window surface, or be produced in situ on the glass either by encapsulation (a process in which the window is placed in a mold which defines the required shape for the polymer profile around the periphery of the glass, and the required solid polymer precursor introduced into the mold cavity in liquid form and cured in situ on the glass), or by extrusion from a suitable shaped nozzle which is advanced around the periphery of the window to form the required frame.
The polymeric profile frames bonded to the vehicle window may serve a variety of functions. For example, in addition to (optionally) providing a "bed" on the glass to receive adhesive for bonding the glazing to the car, they may include inner and/or outer dams for limiting the spread of such adhesive, and distance elements for controlling the distance between the internal surface of the window and the opposing surface of the vehicle bodywork to which the window is to be bonded by adhesive. The frame may project beyond the edge of the glass into contact with vehicle bodywork opposing the edge face of the glass, thereby positioning the window positively within the aperture (see, for example, EP 0 121 480A, FIG. 3, and EP 0 545 896B).
However, providing a polymeric profile in the form of a frame around the periphery of the window requires significant quantities of polymer material (which may be costly) and, if the frame is provided by direct extrusion of the polymer material onto the surface of the window, requires rectification of the joint where the frame is completed, which is liable to be a time-consuming and hence expensive process. Rectification refers to the process of making good the join between the start and end of the extrusion, i.e. making it uniform and hence not readily detectable.